Although the mating surfaces or pairs of surfaces to be sealed, such as an automotive engine block and a mating surface on an exhaust manifold, appear to be smooth and flat, most frequently they are not sufficiently smooth to provide an effective seal. Accordingly, a gasket is required to be placed between them to provide an effective seal against escaping fluids, such as gas vapors.
Multi-layer gasket assemblies are becoming more popular for use with automobile engines. Such a gasket assembly is comprised of two or more layered gasket pieces which are typically welded or riveted to each other. Each gasket piece may be similar in size and overall configuration to other gasket pieces used in the same assembly. Each piece can, however, include details which distinguish it from the other gasket pieces. That is, albeit similarly outlined or configured, one gasket piece may have one or more embossments provided thereon while another similarly outlined gasket piece in the same gasket assembly may have different embossments or other features provided thereon. Additonally, for example, one gasket piece in the assembly may be substantially flat while another gasket piece in the same assembly can include a flow tube extending from a source opening provided in that gasket piece.
Production of multi-layered gaskets typically comprises multiple steps or manufacturing processes. First, because each piece comprising the gasket assembly may be uniquely designed, individualized gasket pieces are mass produced, as by a stamping or blanking process. That is, steel or other suitable gasket material is continuously fed to a machine which stamps or blanks out individual gasket pieces having specific configurations. In the next step, these individual gasket pieces are separately processed, as by heat treating, etc. Then, the individualized gasket pieces are layered in a specific order and are, subsequently, assembled in that order. The individual pieces forming the gasket assembly are usually held together as an assemblage, as with rivets or spot welding. After the separate gasket pieces are joined together as a complete assembly, the resultant gasket is inspected for accuracy and compliance.
It is critical that each piece comprising the gasket assembly is layered in its proper order. Otherwise, the gasket assembly is likely to fail. Because the pieces comprising the gasket assembly may all be similar in size and overall configuration, assembly of the gasket can easily be done incorrectly. That is, gasket pieces may be arranged in an improperly layered order. Alternatively, and because the gasket pieces are individually manufactured, placed together, and then assembled, two of the same gasket pieces may be inadvertently assembled together. A myriad of other inadvertent yet incorrect combinations of gasket pieces is conceivable. Although inadvertent, such improper combinations or arrangements of the various gasket pieces can result in gasket failure.